Answer: Z is approximately A/2 for light nuclei, Z < A/2 for heavy nuclei.
- A Z = A/2 exactly for every stable nucleus regardless of size
- B Z is approximately A/2 for light nuclei, Z < A/2 for heavy nuclei
- C The proton number Z is usually greater than the neutron number N
- D The neutron number N is usually exactly zero as frequently observed in practice
Correct answer: B. Z is approximately A/2 for light nuclei, Z < A/2 for heavy nuclei
Explanation: Light stable nuclei: Z ≈ N ≈ A/2. Heavy nuclei need more neutrons for stability (neutron-proton ratio > 1).
Binding energy per nucleon rises sharply for light nuclei, peaks around iron-56 (the most stable nucleus), then slowly declines for heavier nuclei - which is exactly why fusing light nuclei or splitting heavy nuclei both release energy: each moves the products toward this stability peak.
Concept context
Radioactivity, nuclear reactions, fission, fusion, and binding energy.